Analysis of the cross talk between Ras-ERK and PI3K-AKT signaling pathways reveals integrin β1, myosin light chain kinase (MLCK) and myosin IIA are required for the activation of PI3K-AKT following inhibition of the Ras-ERK pathway. Integrin β1, MLCK, and myosin IIA are factors in the development of resistance to MEK inhibitors.